1. Technical Field
This invention relates to the art of RF amplifier systems and, more particularly, to a system having an improved power supply.
2. Description of the Prior Art
The U.S. patents to H. I. Swanson, U.S. Pat. Nos. 4,580,111 and 4,949,050 disclose an amplitude modulator for use in AM radio broadcasting and wherein the modulator serves to generate an amplitude modulated signal by selectively turning on and off a plurality of RF amplifiers in a digital manner to produce amplitude modulation. Each of the RF amplifiers provides an output voltage across the primary winding of a transformer. The secondary windings of the transformers are connected together in series in a series combiner.
Such systems employed power supply circuits having transformers with multiple winding turns on both the primary and secondary sides.
In accordance with one aspect of the present invention, an RF amplifier system is disclosed having an improved power supply. The supply includes a plurality of power amplifiers each having an output circuit for connecting a DC voltage source with one of a plurality of primary windings located on a first transformer. The amplifiers are controlled by a common controller. The first transformer has a plurality of secondary windings located thereon with the secondary windings each being a single turn secondary winding. The secondary windings are connected together in series such that an output voltage is developed across the secondary windings. The second transformer is located in a cascaded arrangement with the first transformer and has a like plurality of single turn primary windings connected together in series. The single turn primary windings on the second transformer are connected in parallel with the single turn secondary windings on the first transformer. A like plurality of secondary windings are on the second transformer with each being connected to a rectifier for providing a controlled DC voltage.